Even if Greek voters strongly favour "yes" or "no" in the bailout referendum, neither result leads to a clear answer for what Greece should do about its overstretched finances.

A "yes" result would likely produce a national unity government with a new election to follow -- but that would take time, and without financial assistance, the chances of a full, chaotic default would increase.

Since Greece is no longer in a bailout program, it has to negotiate a new one with creditors that involves even more money for its debt-ridden government and the banks and new economic austerity measures. That means banking restrictions on money withdrawals and transfers may remain in place even longer than anticipated.

Despite the Greek government's assertion that a "no" vote will not lead to a "Grexit" -- a Greek exit from using the common euro currency -- most experts agree it would open up more uncertain financial outcomes.

The governing left-wing Syriza party's European member of parliament says that "Greek people are proving they want to remain in Europe" as equal members "and not as a debt colony."

Dimitris Papadimoulis said that the country should wait for the official and final results of Sunday's referendum, and called on his fellow countrymen to remain calm. Three opinion polls conducted during the voting indicate a tight race with a likely win by the "no" vote.

Prime Minister Alexis Tsipras called Sunday's referendum last weekend, urging voters to reject creditor reform proposals. Opposition parties and many European officials have warned that a "no" vote, however, could endanger Greece's position in Europe's joint currency, the euro.

"A new effort is beginning," he said, adding that Tsipras would move fast to conclude a deal with Greece's creditors.

Belgium's finance minister is one of the first eurozone ministers to react to an official projection and opinion polls that the "no" vote will win in the Greece referendum, saying it will complicate matters.

Johan Van Overtveldt insists, however, that the door remains open to resume talks with the Greek government "literally, within hours."

He told VRT network on Sunday that the eurogroup of 19 finance ministers can again discuss measures "that can put the Greek economy back on track and gives the Greeks a perspective for the future."

Officials from the Greek government, which had argued that a 'No' vote would strengthen its hand to secure a better deal from international creditors after months of wrangling, immediately said they would try to restart talks with European partners."The negotiations which will start must be concluded very soon, even within 48 hours," government spokesman Gabriel Sakellaridis told Greek television." We will undertake every effort to seal it soon."

"We don't want austerity measures anymore, this has been happening for the last five years and it has driven so many into poverty, we simply can't take any more austerity," said Athens resident Yiannis Gkovesis, 26, holding a large Greek flag in the city's main square.

German Vice Chancellor and Economic Affairs Minister Sigmar Gabriel said the Greek government is leading its people "onto a path of bitter austerity and hopelessness." He added the Greek prime minister had "torn down the last bridges, across which Europe and Greece could move toward a compromise ... By saying no to the eurozone's rules, as is reflected in the majority 'no' vote, it's difficult to imagine negotiations over an aid package for billions."

European Parliament President Martin Schulz said a summit of eurozone leaders planned for Tuesday should discuss a "humanitarian aid program for Greece" with "meaningful and constructive proposals" in the coming hours to get the talks with the other 18 eurozone nations going again. "If not, we are entering a very difficult and even dramatic time."

Greek police say 100 to 150 anarchist protesters have started throwing firebombs at riot police and setting trash cans on fire in the central Athens neighbourhood of Exarcheia. This is far from the place where celebrations are taking place by supporters of the "no" vote in Sunday's referendum. There was no indication that the violence was connected to the political campaigns involved in the vote.

Dutch Finance Minister Jeroen Dijsselbloem, president of the eurozone finance ministers' group, said: "For the recovery of the Greek economy, difficult measures and reforms are inevitable. We will now wait for the initiatives of the Greek authorities."